Bridge underview device

ABSTRACT

A bridge underview device includes a chassis; a turntable mounted on the chassis and being rotatable about a vertical axis; a bearing element mounted on the turntable by a first pivot joint for a swinging motion about a horizontal axis of the first pivot joint; a guide member; an elevating tower mounted on the guide member for gliding displacement relative to the guide member; a first arm coupled to the bearing element by a second pivot joint and to the guide member by a third pivot joint; and a second arm extending parallel to the first arm and being coupled to the bearing element by a fourth pivot joint and to the guide member by a fifth pivot joint. The second, third, fourth and fifth pivot joints each have a horizontal axis, whereby the guide member and the elevating tower are swingable as a unit relative to the bearing member in a vertical plane while maintaining an unchanged orientation. There are further provided positioning devices for maintaining the bearing member in a desired angular position relative to the chassis and for maintaining the guide member in a desired distance relative to the bearing member.

BACKGROUND OF THE INVENTION

The invention relates to a raisable and lowerable elevating tower whichextends downwards over the bridge edge and to which is fitted a workplatform projecting beneath the bridge, and having a chassis located onthe bridge and exhibiting a bearing element which is vertical in theworking position and is connected to the elevating tower by means ofarms protruding over the bridge edge.

A device of this kind is known, for example, from European DisclosureSpecification 156 304. As a vertical bearing element, there is hereprovided a so-called guide tower of considerable height. On its sidepointing, in the operating position, towards the bridge edge, it hasguide rails, in which a slide is guided which can be moved up and downby means of a lifting cylinder. To the slide are fastened jibsprojecting perpendicularly to the guide tower, i.e. horizontally, whichare firmly connected to the elevating tower. The rigid structural unitcomprising elevating tower, jibs and slide is thus guided on the guidetower. The vertical position of the jibs determines the verticalposition of the work platform.

Often it is necessary to cross over high obstacles disposed on thebridge edge, e.g. protective fencing, soundproofing walls or lightingmasts, with the jibs. Although this can be done by using a sufficientlyhigh guide tower, the elevating tower can then no longer be moved in avertical direction in order to bring the work platform to the correctdistance from the underside of the bridge support.

A further problem presents itself in connection with so-called trussbridges, the girders of which located at both sides of the carriagewaycomprise mutually alternating vertical columns and oblique ties, whichare connected to one another at the top by horizontal trusses. Here, oneis forced to reach with the jibs through the windows formed from column,tie and truss, to be precise, over or under the oblique tie. Dependingupon the pattern of the latticework, this necessitates, at variouslocations along the bridge, different heights for the work platform,which is unacceptable.

SUMMARY OF THE INVENTION

The object of the invention is to propose a self-erecting bridgeunderview device, which crosses over high obstacles on the bridge edgeand oblique lattice ties whilst allowing the height of the work platformto be altered, and is easy to construct and simple to use.

This object is achieved according to the invention, in the case of abridge underview device of the generic type, by the elevating towerbeing received by a guide member and being movable in relation to thisin the longitudinal direction of the tower, and by the arms beingattached, in a horizontally axial manner, at one end to the bearingelement and at the other end to the guide member and forming a doubleparallelogram, and by the arms, in relation to a mid-positionperpendicular to the elevating tower, being free to swivel out to bothsides.

In place of a guide tower, a relatively low bearing element is providedin the form of an essentially rectangular frame, to which a total of atleast four mutually parallel running arms are directly attached. On theelevating tower side, the arms are attached to a guide member, on whichthe elevating tower is guided in vertically movable manner. Preferably,the arms are of such a length that, between the downwardly and upwardlypivoted end positions of the guide member, a height difference of atleast 1.5 m or so can be obtained.

The vertical position of the elevating tower and of the therebysupported work platform can therefore be altered by two mutuallyindependent means, firstly by moving the elevating tower in relation tothe guide member and secondly by pivoting the arms up and down. Thistwin vertical adjustment facility enables the device to be used in thecase of truss bridges, for, when the arms have to be pivoted downwards,the elevating tower can move correspondingly upwards and vice versa.

Since the vertical-adjustment ranges are added together, the range ofadjustment of the elevating tower can be relatively small in relation tothe guide mechanism, so that, with considerable cost savings, a simplelifting cylinder can be used in place of a telescopic cylinder.

Preferably, the double parallelogram formed by the arms can be actuatedby means of at least one lifting cylinder acting obliquely upon the armsor upon the guide member on the one hand and upon the bearing element onthe other hand.

For installation, it is advantageous if the chassis exhibits a turntablewhich is pivotable about a vertical axis and if the bearing element isadjustably mounted on this such that it can be pivoted about ahorizontal axis. By slightly altering the angular position of thebearing element, any transverse inclination of the carriageway can beoffset, as can a lateral inclination of the chassis relative to thecarriageway caused by a road shoulder or similar.

In order to be able, where required, to cross over particularly widebarriers at the bridge edge and, when the arms are pivoted up and down,to obtain yet greater height differences for the guide member, the armscan have a length-adjustable configuration.

The pivotability of the arms also has the advantage that the transportheight, i.e. the height of the bridge underview device when loaded forroad transport onto a vehicle, can be kept small. In this case, thebearing element is found in horizontal position and the elevating towerplus guide member parallel above it. By tilting the arms, the elevatingtower can thus be lowered and the total height reduced.

The described device allows a particularly comfortable and secure climbfrom the chassis to the elevating tower, since the two lower arms areconnected to each other by a base. The distance between this base andthe upper arms, which are transversely brace-connected to one another,can amount to 2 m, for example, so that it is possible to walk uprighton the traversing bridge. At the side, pliable railings can be fitted.

In individual cases, in order once again to gain extra height forcrossing over soundproofing walls or similar, it is expedient if thelower arms on the bearing element and on the guide member an bedisplaced, according to choice, into higher placed articulated eyes. Thegained height reduces however the standing height on the traversingbridge. This can be countered by an extension of the bearing element andby a V-shaped arrangement of the cross-ties between the upper arms. AV-arrangement of this kind reduces the risk of one's head knockingagainst it.

The described bridge underview device is extremely flexible in its use.It can even be erected when the space above the carriageway, e.g. in thecase of motorway junction constructions, is restricted by a furtherintersecting carriageway. High obstacles at the edge of the carriagewaycan be crossed over, without the vertical mobility of the work platformbeing thereby impaired. On the other hand, the elevating tower, when thearms are angled downwards, reaches extremely low under the bridge, sothat even very tall bridge supports can be inspected from below from thework platform.

BRIEF DESCRIPTION OF THE DRAWING

An illustrative, preferred embodiment of the invention is explainedbelow with reference to the drawing. More specifically,

FIG. 1 shows a view of the top part of a bridge underview device inoperating position, viewed in the longitudinal direction of the bridge,and

FIG. 2 shows a top view of the device according to FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The bridge 1 has, in the example, a railing 2. The function of thechassis is performed by a lorry 3, exhibiting a swiveling bolster 5,which is rotatable about a vertical axis 4. A bearing element 7 having ahorizontal axis 6 is pivotably mounted on this bolster, which bearingelement is configured as a rectangular frame through which the operatingstaff can climb into the elevating tower 8. By means of a liftingcylinder 9, which is attached at 10 to the bearing element 7, thebearing element 7 is pivoted from its horizontal transport position, inwhich it rests on the swiveling bolster 5, into the vertical workingposition shown.

Arms 11, 12 are attached to the bearing element 7, these beingconfigured as double arms or frames (not visible in the side view). Thearms 11, 12 are attached by their left ends to a guide member 13. The,in each case, horizontal articulated axes of the upper arm 11 aredenoted by 14 and 15 and those of the lower arm 12 by 16 and 17. Twolifting cylinders 18 serve to actuate the arms or the doubleparallelogram formed by them, these lifting cylinders being attached at19 and 20, i.e. high up on the guide member 13 and just below the centreof the bearing element. The guide tower 8, to the lower rotatable partof which a non-illustrated work platform is fitted, is only showndisplaying its upper part. Its two corner uprights 21 adjoining thebridge 1 are reinforced and configured as guide rails, in which therollers 22 or corresponding sliding elements of the guide member 33 areable to move along. The lifting cylinder, which moves the elevatingtower in relation to the guide member, is not shown.

From the top view according to FIG. 2, the counterbracing of the twoupper arms 11 can be particularly clearly seen, namely a cross-tie 23and two ties 24 in V-shape arrangement each. The vertical uprights ofthe bearing element 7 are connected to one another at the top by acrosshead 25. The guide member too, has a two-legged configuration andis transversely braced. The swiveling bolster 5 is shown only infragmentary representation in the top view.

If the lifting cylinder 18 is extended, the arms 11 and 12 pivot upwardsand correspondingly downwards when the lifting cylinder 18 is completedretracted. These end positions are in each case indicated by dot-dashlines. A central position of the arms 11, 12 between the two endpositions is shown in solid lines. In such a central position the guidemember 13 is at a maximum distance from the bearing element 7. Upon thispivotal movement, it is not only the height of the guide member 13 andof the thereby supported elevating tower which changes advantageously,but also its distance from the bridge. A transverse inclination of thebridge surface can be offset by readjusting the lifting cylinder 9, i.e.in this case, also, the elevating tower stands vertically.

Starting from the shown operating position, the dismantling of thedevice into the transport position is carried out as follows: firstly,the work platform (not shown) is pivoted outwards and then folded upagainst the elevating tower. The elevating tower 8 then travels to abouthalfway up, i.e. approximately into its position of equilibrium inrelation to the arms 11 and 12. The bearing element 7, by the retractionof the lifting cylinder 9, now folds down onto the vehicle; the arms 11and 12 stand in their mid-position at right angles to the bearingelement 7 and to the elevating tower 8. As a result of the pivotalmovement of the bearing element 7, the tower rises and pivots by itsbottom end away f rom the bridge and by its upper end over onto thebridge. During the pivoting movement, the swiveling bolster 5 alreadybegins to rotate, the upper elevating tower end still having a height ofaround four meters above the carriageway, so that, on the driving lanerunning next to the lorry 3, vehicles are able to drive throughunderneath it. Once the parallel position to the vehicle has beenreached, the arms 11 and 12 are slightly pivoted and the guide member 13thereby lowered somewhat. The elevating tower 8 now rests upon fixedmountings on the roof of the driver's cab and on the tail side of thevehicle.

It should be regarded as a particular advantage of the described devicethat the lifting movement which can be achieved by tilting the arms 11and 12 can only be achieved by driving the lifting cylinder 18 in anexactly vertical direction. The climb to the elevating tower 8 isunproblematical. The arm 12 acts in this regard as a bridge or ramp,which can be traversed without hesitation, even in an inclined position,provided a suitably grip-fast grille is used. In the case of yet greaterinclinations, a stairway having swivel steps can also be used.

As a result of the shortening and reduction in size of the bearingelement 7 in comparison with the known elevating tower, substantialspace savings are achieved in the transport position in front of andbehind the bearing element and the arms 11 and 12 on the loading planeof the vehicle. In particular, cabins can be installed at theselocations, which could serve as lodgings, for the duration of the works,for staff working on the bridge.

We claim:
 1. A bridge underview device comprising(a) a chassis; (b) a turntable mounted on said chassis and being rotatable about a vertical axis; (c) a bearing element mounted on said turntable by a first pivot joint for a swinging motion about a horizontal axis of said first pivot joint; (d) a guide member; (e) an elevating tower; (f) mounting means for mounting said elevating tower on said guide member for gliding displacement relative to said guide member; (g) a first arm coupled to said bearing element by a second pivot joint and to said guide member by a third pivot joint; (h) a second arm extending parallel to said first arm and being coupled to said bearing element by a fourth pivot joint and to said guide member by a fifth pivot joint; said second, third, fourth and fifth pivot joints each having a horizontal axis; said first and second arms being swingable in unison to either side beyond a central position of said first and second arms for swinging said guide member and said elevating tower as a unit relative to said bearing member in a vertical plane while maintaining an unchanged orientation; in said central position said guide member being at a maximum distance from said bearing element; (i) first positioning means for maintaining said bearing member in a desired angular position relative to said chassis; and (j) second positioning means for maintaining said guide member in a desired distance relative to said bearing member.
 2. The bridge underview device as defined in claim 1, wherein said first and second arms, a length portion of said bearing element between said first and second arms and a length portion of said guide member between said first and second arms constitute a parallelogram having sides articulated to one another.
 3. The bridge underview device as defined in claim 1, wherein said second positioning means comprises power means for displacing said guide member and said elevating tower as a unit relative to said bearing element.
 4. The bridge underview device as defined in claim 3, wherein said power means comprises a lifting cylinder assembly having a first end articulated to said bearing element and a second end articulated to said guide member.
 5. The bridge underview device as defined in claim 1, wherein said first and second arms are length-adjustable. 